Stopping ADHD medication alters sleep rhythms long after discontinuation

Stopping the common attention-deficit/hyperactivity disorder medication methylphenidate can cause lasting disruptions to sleep and activity rhythms. In a recent animal study, researchers found that both adolescent and adult rats experienced reduced rest quality ten days after they stopped taking the drug. The research was published in the journal Psychopharmacology.

Children and adults with attention-deficit/hyperactivity disorder, or ADHD, often experience higher rates of sleep disturbances than their peers. These issues range from difficulty falling asleep to experiencing fragmented and shortened periods of rest. Because sleep problems are so common in this population, medical professionals increasingly view ADHD as a condition that affects people throughout the entire day and night.

The most frequently prescribed treatment for pediatric ADHD is methylphenidate. This psychostimulant helps improve attention and reduce hyperactivity. Patients taking the drug occasionally report side effects like delayed sleep onset and insomnia.

Treatment discontinuation among people with ADHD is highly prevalent. Medical data suggests that a large portion of patients eventually stop taking their prescribed psychostimulants, with the highest dropout rates occurring among young adults.

Researchers have debated whether the medication itself worsens existing sleep disturbances or contributes to new sleep disorders later in life. Much of the existing data focuses on the drug’s effects while a patient is actively taking it. Very few clinical or laboratory studies have tracked what happens to sleep patterns once the medication is stopped.

To answer this question, researchers led by psychologist Leslie R. Amodeo and graduate researcher Carolyn Cueto at California State University, San Bernardino, designed an experiment using an animal model. By observing rats without an underlying disorder, the team aimed to isolate the physiological effects of the drug from the behavioral symptoms of ADHD. They investigated how methylphenidate influenced the natural rest and wake cycles of male and female rats during both adolescence and adulthood.

The experiment involved one hundred and eight Long-Evans rats divided into groups of 56 adolescents and 52 adults. The animals received either a saline control injection or a specific dose of methylphenidate twice a day for ten days. The researchers administered doses of one or two milligrams per kilogram, which correspond to clinically relevant levels in human patients. To mimic the prolonged exposure typical of medical treatment, the researchers administered the drug in the morning and the evening.

To measure activity levels, the researchers fitted each rat with a customized spandex jacket equipped with a lightweight commercial activity monitor. These monitors tracked the animals’ physical movements continuously throughout a twenty-four-hour cycle. Rats are nocturnal animals, meaning they are naturally active in the dark and rest when their environment is brightly lit.

The research team gathered minute-by-minute movement data on three specific days. They analyzed activity on the final day of the medication regimen, on the first day after the drug was stopped, and ten days after the treatment ended.

On the final day of treatment, the medication increased overall activity levels across both the light and dark phases. Adult rats receiving the higher dose experienced longer and more frequent active periods during their usual waking hours in the dark. The researchers also noticed shifts in the timing of the animals’ daily circadian rhythms, with peak activity occurring later than usual.

The medication altered the quality of rest during the light phase as well. Female rats in particular showed signs of impaired rest on the last day of the drug regimen. They experienced fewer total rest periods and exhibited more fragmented sleep patterns compared to those receiving the saline control.

The researchers then stopped the injections and observed the animals during the first twenty-four hours of withdrawal. During this acute discontinuation phase, the rats’ activity patterns began to shift in the opposite direction. The previously sustained periods of wakefulness seen in adult rats shortened and became more erratic.

During their normal resting phase in the light, the rats undergoing acute withdrawal continued to experience sleep disruptions. Adolescent rats that had received the lower dose of the drug showed shorter rest episodes than their peers in the control group. Both male and female rats experienced an increase in rest fragmentation, meaning their periods of stillness were frequently interrupted by bursts of movement.

The most pronounced impairments emerged ten days after the animals stopped taking the medication. During this prolonged withdrawal phase, widespread disruptions to rest quality appeared across all age and sex groups. Rats that had been given methylphenidate experienced a drop in both the total number of rest episodes and the average duration of each resting period.

The activity monitors revealed that the animals’ sleep-like states remained highly fragmented long after the stimulant had left their biological systems. Sleep fragmentation involves frequent physical arousals that interrupt continuous rest. In human populations, this type of fragmented rest is linked to memory impairment, increased physical stress, and metabolic dysfunction.

While the findings demonstrate a link between methylphenidate withdrawal and altered rest patterns in an animal model, rats process medications differently than humans. The rats used in this study also did not have a neurological equivalent of ADHD. People taking the medication for a diagnosed condition might experience different physiological responses than a non-diseased animal subject.

The researchers measured sleep-like behavior using activity monitors that track physical movement rather than brain waves. True sleep architecture requires monitoring electrical activity in the brain to identify specific sleep stages. Relying on physical stillness provides a useful approximation for rest, but it does not capture the deeper neurological shifts associated with entering deep sleep.

Future research will need to explore exactly how early exposure to stimulants alters the brain’s long-term sleep and arousal circuitry. Previous rodent studies have suggested that withdrawing from stimulants can alter glucose metabolism in the hypothalamus, a brain region critical to regulating wakefulness. Researchers hope to determine if these prolonged sleep disturbances contribute to changes in cognitive function or reward processing later in life. Understanding these extended withdrawal effects could help doctors better manage the treatment plans of patients who eventually stop taking their medication.

The study, “Methylphenidate leads to disruptions in rest/wake patterns after discontinuation,” was authored by Carolyn Cueto, Magdalena R. Gonzales, Alexandra N. Tejada, Kimberly Guerrero Leon, Alexandra Mora, Andrew Cabrera, and Leslie R. Amodeo.